FIG. 1 is a view showing an example of a conventional microspeaker.
A yoke 21, an inner ring magnet 22, an outer ring magnet 23, an inner ring top plate 24, and an outer ring top plate 25 are installed within a frame 10, and a voice coil 30 is placed in air gaps between the inner ring magnet 22 and the outer ring magnet 23 and vibrates vertically when power is applied to the voice coil 30. The voice coil 30 is mounted to the bottom side of a suspension 40, and a side diaphragm 51 and a center diaphragm 52 are installed on the top and bottom sides of the suspension 40 and vibrate in synchrony with the vibration of the voice coil 30, producing a sound. A protector 60 is connected to the top of suspension 40 to protect the parts located inside a speaker. The protector 60 includes a ring-shaped steel portion 61 with an opening in the middle to emit a sound, and a ring-shaped injection portion 62, through which the steel portion 61 is inserted and injection-molded and which is laminated on top of the frame 10, the outer periphery of the side diaphragm 51, and the outer periphery of the suspension 40.
Conventionally, a bond or double-sided tape has been used to attach the side diaphragm 51 and the center diaphragm 52 to the suspension 40. However, there is a drawback that, though the bond has high bonding property, it causes a large deviation in application thickness and a deviation in laminate thickness of a sound transducer, thereby causing non-uniformity in the quality of finished products. In addition, the double-sided tape causes little deviation in thickness but has low adhesion.